Nowadays, personal mobility vehicles have been attracting attention. A personal mobility vehicle is often manufactured in a small size in view of maneuverability, which raises a problem that it lacks stability when traveling at a high speed. In order to improve stability of vehicles, including personal mobility vehicles but not limited thereto, vehicles having adjustable wheel base lengths have been suggested (e.g., Japanese Unexamined Patent Application Publication Nos. H1-106717 and 2005-231415).